Bell Housing Bushing

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john keefe
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Bell Housing Bushing

Post by john keefe » Sat Mar 21, 2020 5:52 pm

Now that I have some free time, I'm checking out a spare A4 that had been sitting for some time. Have no history on it, but its exceptionally clean. Almost no clutch-gunk in the oil or pan, no metal (not even on the magnet) though it looks like it had been run for 1-2K miles before being pulled. With the caveats that I don't know who did it, or how extensive (soft vs. complete), somebody had gone through it and replaced the VB and bell-to-case gaskets with new TransTec's .

I pulled the VB, and there was no carbon gunk under the clutch waste-chutes. Everything looks exceptionally clean from the VB side, but we'll see how good if/when I can start exploring.

The only thing which appears questionable so far is that the TCC/bell bushing has a couple small scores in it. I'm only examining through the front seal, but they look shallow, and only track about 1/3 of the circumference. The rest of the bushing looks good. Maybe a tiny piece of metal scored the bushing, but didn't "ride" all the way around the bushing. No fretting or galling over the width of the bushing as you'd expect if the TC was riding off center, just one or two grooves from what I can see.

It's probably the original bushing, since the front seal has only the factory stake(swage) marks. (i.e., you wouldn't leave the seal in while machining the new bushing).

I could only find one shop around here which said it would/could install a new bushing, and machine it out to the centerline of the bell housing (i.e., machined "in place," per the manual), but they want $275.00 !

What to do with the bushing?

So, whether a soft or complete rebuild, I'm guessing that the new bell-to-case gasket means the bell was pulled to work on the internals. And, since the front seal is original, I'm hoping a competent tech must have looked at the bushing and thought it good enough to leave it alone, rather than mess with machining a new one. I don't know this, just hopeful. Who knows if it had the score in it at the time, or if that came after the rebuild.

But, since its original, and everything I've read says to leave that bushing alone if the clearances are within spec for the TC:

a) Would you leave it in place, and scrape down the "high" ridges of the scored lines; or,

b) Scrape it, and do a very mild hone of the bushing; or

b) Mic the bearing all around to see if its concentric to the casting on the bell housing, and if so then just install a DIY new bushing and hone it (if needed) to minimal clearance with the TC?

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brokencase
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Re: Bell Housing Bushing

Post by brokencase » Mon Mar 23, 2020 9:24 pm

Are the clearances are within spec for the TC? If so than leave it.

You seem to have all the information to make a wise choice, but we are at a bit of a disadvantage because can't see what you describe.

john keefe
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Re: Bell Housing Bushing

Post by john keefe » Mon Mar 23, 2020 9:38 pm

"Wise" and my name are not usually colliding in the same sentence.

john keefe
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Re: Bell Housing Bushing

Post by john keefe » Mon Mar 23, 2020 9:41 pm

I know its a big ask without pics. If it was a tractor, I'd say leave it, but I don't know how much can be tolerated with the TC in these thangs. I guess as long as it's scraped/polished so there's no high edges in gouge, its probably good enough? Consider it extra oiling surface.

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Re: Bell Housing Bushing

Post by john keefe » Fri Apr 03, 2020 7:20 pm

So, with a little time on my hands, I pulled the bell, unbolted the front pump, pulled the front seal, and then drilled the drain-back holes in the bell and the pump to 5/16".

Looked at the bushing, and it was questionable. Figured it wasn't worth the work to do everything else and not make sure the bushing was centered, so I loosely reassembled the bell & pump, got a new bushing, front seal and TC, and took it to the highest rated transmission shop in San Jose.

Unbelievably, they installed the new bushing, turned the TC hub so it was exactly true in diameter (the hub had a slight run-out), then align-bored the bushing, aligned & installed the front pump, and then installed the front seal.

Cost? $0.00 !!!! I gave them $30 for a case of Modello, and everybody was happy. :D :D

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